Gambling is just so addicting because of the fact that you can win money at the first place and because its a game and games can be highly addictive if you play them for a while and you find them enjoying.
Only money is not enough which will make gambling as more addictive but along with earning money when fun and entertainment also invlve then people become more addictive to these games.
but to me there is no fun and enjoyment in gambling if you are not making money, so we can say that fun and enjoyment also depend on the money making in gambling. so addiction in gambling is only because of making money.